Metering pump

ABSTRACT

A precision metering pump of the positive-displacement type in which a variable-stroke drive means including a swivel lever permits adjustment of the volumetric displacement with a high degree of accuracy and constancy between zero and a maximum while the pump is in operation. The pump is self-priming and particularly useful in chemical processing and control operations by reason of construction of the cylinder and piston of highly corrosion-resistant ceramic and plastic materials, and provision of sensitively adjustable magnetic valve means eliminating metallic springs and parts subject to chemical action in a flow line.

United States Patent [191 Krebs et al.

[451 Sept. 10, 1974 METERING PUMP [76] Inventors: Frank Krebs, Glenview;Frederick N. Zimmermann, Deerfield, both of 22 Filed: Aug. 30, 1971 21Appl.No.: 175,842

52 U.S.Cl 417/505, 92/131,417/0101 51 Int. Cl. F04b 39/08 [58] Field ofSearch 417/505, 567; 92/13, 13.3, 92/134, 13.41, 13.7,170, 248

[56] References Cited UNITED STATES PATENTS 1,133,778 3/1915 Wrightson,Jr. 92/248 2,043,424 6/1936 Campbell 92/212 X 2,607,342 8/1952 Abel92/170 X 2,780,404 2/1957 Kuehni 92/137 2,908,288 10/1959 Carr et al137/540 3,171,287 3/1965 Jesse 92/13.? X

3,306,212 2/1967 Norton 92/137 X 3,326,087 6/1967 Gohlke et a1. 91/2753,485,441 12/1969 Eaton, .Ir. 417/505 3,489,099 l/l970 I-Iuffsmith, Sr92/248 FOREIGN PATENTS OR APPLICATIONS 873,057 3/1942 France 1. 92/137Primary Examiner-William L. Freeh Assistant ExaminerLeonard SmithAttorney, Agent, or FirmCallarc1 Livingston [57] ABSTRACT A A precisionmetering pump of the positivedisplacement type in which avariable-stroke drive means including a swivel lever permits adjustmentof the volumetric displacement with a high degree of accuracy andconstancy between zero and a maximum while the pump is in operation. Thepump is selfpriming and particularly useful in chemical processing andcontrol operations by reason of construction of the cylinder and pistonof highly corrosion-resistant ceramic and plastic materials, andprovision of sensitively adjustable magnetic valve means eliminatingmetallic springs and parts subject to chemical action in a flow line.

PAIENIEDSEPWIW mamas INVENTUBZ Y Fran/Q Xreba X,

METERING PUMP The principal object of the invention is the provision ofa self-priming metering pump of the positivedisplacement type havingcylinder, piston and valve means constructed from highlycorrosion-resistant nonmetallic materials adapting it for use insensitive chemical processing and control operations and capable ofworking at relatively high pressure with progressive adjustment over itsentire displacement range, rather than by stepped increments, and havingsuch a degree of accuracy and constancy as to make it dependable incritical control applications.

To such ends the invention is characterized by and the disclosuresprovide a ceramic pumpcylinder and a composition piston formed ofnon-metallic materials including one or more bearing substances,together with magnetic valve means employing substantially metal-freeceramic magnets acting in polar opposition and capable of sensitive flowadjustment and antisiphoning shut-off, with continuous volumetric adjustment achieved through a simple variable-stroke drive means comprising anadjustment swivel concentric with a drive shaft and an eccentric.thereon cooperative with lost-motion means to impart adriving stroke ofselected amplitude to the piston depending uponthe angular setting ofthe swivel.

More particular objects and features of novelty and utilitycharacterizing the invention relate to detailed aspects of theconstruction and operation of the illustrative embodiments describedhereinafter in view of the annexed drawingsin which:

FIG. 1 is a perspective view of the complete pump assembly withenclosing hood and shroud components;

FIG. 2 is an enlarged front elevation of the assembly of FIG. 1 with thepump shroud removed;

FIG. 3 is a side elevation of the unit with both motor hood and pumpshroud removed;

FIG. 4 is a horizontal cross section through the valve head lookingalong lines 4--4 of FIG. 2;

FIG. 5 is an exploded detail of one of the magnetic valves taken toenlarged scale;

FIG. 6 is an end view of one of the magnetic valve plungers;

FIG. 7 is an exploded perspective detail of piston drive components;

FIG. 7A is a side elevation of the adjustment swivel;

FIG. 8 is a front elevational view of the pump with a modifiedadjustable piston drive means;

FIG. 9 is a fragmentary front detail of the drive means of FIG. 8 withbracket parts broken away;

FIG. 10 is a detail of parts seen in FIG19 but viewed from the side;

FIG. 11 is a perspective detail of the adjusting lever seen in FIG. 8.

A complete pump unit of a type adapted to general use is depicted inFIG. 1 and comprises a base plate 10 on which is footed an uprightmounting plate 11 stabilized by brackets 11A with the pump mechanismmounted on the forward side of the plate but normally concealed behind aremovable shroud 12, and a driving motor situated on the opposite sideof said plate beneath a hood structure 13.

In the view of FIG. 2, the shroud plate has been removed from itsmounting block 15 revealing the pump mechanism comprising a cylinder 14having an upper open end portion sealed within a bore formed in a valveblock 16 secured to plate 11 and having outlet and inlet nipples l7 and18 with appertaining valve means for connection into a flow line. In thedrawing the valve head block 16 and parts of the valve structure areshown for illustrative purposes as made from a clear plastic material,but opaque plastics materials such as Penton (TM) are recommended forgeneral chemical usage. Ducts 17B and 18B communicatefrom the nipples tovalve bores 17A, 18A.

Formed in the valve block 16 are valve bores 17A and 18A interconnectedby a flow passage "19 which in turn is intercepted by a cylinder duct 20communicating into the upper end of the cylinder 14 (FIGS. 2, 3 and 4).Reciprocable in each valve bore is a corresponding valve plunger orpoppet 21A or 218 (the valves being identical) which is of the generallytubular cylindrical configuration seen in FIGS. 5 and 6 and havingcircumferentially spaced apart longitudinally extensive slide ribs orrunners 23 on its external surface to reduce the frictional area andwetting drag in the bore.

Each valve plunger 21A or 213 is hollow and open at one end to receive acylindrical permanent magnet 24A or 248, while the opposite end isclosed with a conical nose2lA' seating in a matching conical valve seatformed in the valve block at a juncture with the flow passage 19, as inFIG. 4. Fine air relief holes 25 penetrate the tubular walls of thevalve plungers to relieve compression and-suction .in the zone betweenthe juxtaposed ends of the actuating magnets forming part of each valveunit.

Each of the valve bores 17A or 18A is partially threaded at its entranceto receive corresponding screw plugs 26A or 268 which constitute acombination closure and adjusting means (FIGS. 4 and 5), each said plughaving the threaded shank portion thereof bored to form a socket for thecorresponding actuating magnet 27A or 27B.

Thus, each valve unit has a set of magnets, including a driven magnet,such as 24A, within the appertaining valve plunger or poppet, and acompanion driving and control magnet 27A within the correspondingadjustment screw plug 26A, the magnets in each set being coaxiallyaligned with respect to their magnetic axes and the turning axis of thescrew plug. By arranging the two magnets in each set so that theirproximate poles are alike, that is to say so that either twosouth-seeking or two north-seeking poles are juxtaposed, the magnets ofeach set 24A and 24B, for example, are repulsed by their correspondingdriving or actuating magnets 27A or 278 and thereby forced to seat inthe valve-closing condition with a force which can be regulated byturning in the appertaining screw plugs in their respective threadedbores, such adjustment being very sensitive owing to the square-lawaction of the magnetic forces acting to seat the valve plungers.

The pump cylinder 14 is formed of a substantially chemically inertmaterial such as procelain or the like having minimal silica content andhigh resistance to caustic and aciduous agents, and the associatedpiston 40 is likewise made of an equally inert materials but having, inaddition, desirable bearing qualities, for which purpose it has beenfound that a mixture of a fluorocarbon material such as teflon with afiller of Molybdenum and graphite is suitable.

The magnets in the valve units are of the so-called ceramic type formedof barium ferrite and having minimal or no free iron or metal contentlikely to be attacked by, or to contaminate, the pumped liquid, byreason of which these valves eliminate conventional metallic valvesprings which are highly vulnerable to corrosion in many chemicalprocessing operations.

As viewed in FIG. 7, the piston 40 will normally be provided at itsupper end with sealing means such as a pair of acid-resistant pistonrings 41 seated in circumferential grooves to render the pump effectiveeven in relatively high-pressure applications, for example, up to 160psi. At its lower end the cylinder is provided with a lengthwise slot 42communicating through the side wall into a short axial bore formedthereat to receive one end of an offset or dog-leg drive link 43pivotally connecting with the piston by pin means 44, through slot 39.

The opposite end of the offset piston link 43 is fitted with a bearingmeans 45 adapted to engage one end of a coupling pin 46 fixed at one ofthe ends of a connecting rod or crank 47 (FIGS. 2, 3 and 7), while theremaining end of said link is provided with another bearing 48 engaginga tapped eccentric crank pin 49 with which it is pivotally secured byscrew means 49.

The eccentric is fast by means of a set screw on the power shaft 50rotated by motor means 51 and the associated reduction gear means 52,FIG. 3. The pivotal connection 46 between the crank rod 47 and thedogleg driving link 43 is constrained to follow a guided arcuatestroke-regulating path by reason of its projection into an arcuateguideway 55 formed in an adjustment swivel member 56 having a widecentral bore surrounded on its rearward side by an outwardlyprojectingcollar 57, FIG. 7A, which fits rotatively into the seating hole in theupright plate 11 (FIG. 2) which also serves as a bearing for theadjustment motion of the swivel concentrically about the axis of thepower shaft 50 and the eccentric 49, such swivel motion being for thepurpose of changing the angular attitude of the stroke-regulatinglost-motion guideway and consequently the permitted magnitude of thethrow of the piston link 43. The more nearly horizontal the attitude ofthe arcuate guideway 55 relative to the axis of the power shaft, theshorter will be the driving stroke of the link 43 and therefore thesmaller will be the resultant displacement of the piston. Conversely,the greater the downward inclination of the arcuate guideway 55 (belowthe almost horizontal minimal-stroke setting shown in FIG. 2) the longerwill be the driving stroke of link 43 and the greater will be the pistondisplacement.

The permitted angular range of adjustment for the swivel member isdetermined by another arcuate slot 58 formed as a part thereof (FIG. 2)and the clamp screw 60 projecting therethrough as a limiting stop inboth directions of movement. Adjustment of the swivel control lever isfaciltated by provision of a finger tab 59 projecting well beyond theedge of the upright mounting plate 11; and suitable scalar graduations61 may be displayed adjacent thereto on said plate to indicate thesettings in desired terms of volumetric, percentile or other scalarvalues of displacement per stroke or per minute, etc.

The selection of settings afforded by the disclosed variable-strokelinkage means is continuous in very minute increments or decrementsbetween the angular limits of travel of the swivel lever to cover arange from zero to maximum displacement with consistent accuracy andreproducibility even in the case of pumps manufactured to ordinaryproduction tolerances, while pumps machined to close tolerances exhibithigh performance accuracy within 1 per cent and better.

A modified form of variable-stroke metering pump drive is depicted inFIGS. 8 to 11 wherein substantially the same assembly of pump elementsis employed in respect to the use of an identical base and upright platestructure 10X, 11X, as well as cylinder, valve and piston means 14X,16X, 26AX, 26BX and 40X, which are the same as described for theembodiment of FIGS. 1 to 7, the modification, however, employing adifferent piston drive means, as in FIG. 8, wherein the lower end of thestem of the piston is fitted with a frusto-conical collar at theunderside of which are trunnions 71 journalling a cam roller 72 adaptedto engage a driving cam 80 rotated by motor shaft 50X (FIG. 9).

A stroke-adjusting swivel lever 75 is pivoted on pin means 79 supportedbetween the upright plate and a bracket member 78 affixed to the baseplate. As depicted in FIG. 11, this swivel lever is a unitary structurepreferably molded from a synthetic plastic material such as Nylon toinclude a finger tab 73, an arcuate clamp screw slot 74 for clamp screw74X, a pivot hub 76, and a bifurcated end formation providing spacedpawl 77 which underlie the piston collar 70 and straddle the cam roller72.

A compression spring 69 is fitted loosely about the piston cylinder toexpand between the valve head 16X and the collar 70 to urge the pistonin the direction of retraction to a lowered position determined by thesetting of the swivel lever and consequent elevation of the pawls 77,from which position the rotating drive cam 80 acting on the roller means72 will drive the piston upwardly in its pressure stroke a distancedepending upon the relative starting position determined by the settingof the pawls, it being possible to depress the lever 75 to its lowerlimit and thereby elevate the piston toward its upper limit an amountsufficient to cause the roller 72 to stand wholly clear of the drivingperiphery of the cam 80 with a consequent zero movement of the piston asthe cam rotates; and conversely, by swinging the lever 75 to its upperlimit of travel the pawls 77 will be lowered to the maximum so that thecam roller can engage the driving cam throughout its cycle and producethe maximum driving stroke for the piston.

Both forms of piston drive afford the advantage of permitting adjustmentof the piston stroke between maximum and minimum volumetric displacementlimits while the pump is in operation, although the action of each isdifferent in the respect that the driving force acting on the cam rollerin the embodiment of FIG. 8 is momentarily discontinuous in all settingsexcept that for maximum piston stroke, there being in the other settingsa brief interval in each cycle of the cam during which the roller 72 isheld beyond driving engagement therewith because the setting of theswivel lever in such cases does not permit the piston to descend farenough to follow the cam completely throughout its 360 travel, whereasin the variable stroke linkage embodiment of FIG. 2 there is no similardiscontinuity and the driving action is in effect continual but for aninstant of zero motion as the travel reverses.

Where the high corrosion resistance and sensitivity of the novelmagnetic repulsion valve means is not required, other forms of valve maybe substituted; for example, plastic-ball or similar poppets andconventional seating springs (not illustrated) may be used insubstantially the same valve bores and seats in replacement of themagnet-carrying valve elements and their respective repulsion magnets,in either embodiment.

The motor drive means for the embodiment of FIG. 8 (not seen) isidentical to that shown in FIG. 3 except that the drive shaft 50X isextended outwardly farther for full engagement with the cam 80, and isaccordingly given extra support in a Nylon bushing block 81 affixed asat 82 to bracket 78.

We claim:

1. In a pump for metering chemical solutions of caustic and acidiccharacter, a cylinder, a piston reciprocable in said cylinder, drivemeans including a shaft rotatable about a first axis extending in adirection at one side of and at right angles to a second axis relativeto which the piston reciprocates, and variablestroke mechanism drivinglyinterconnecting said shaft and piston and comprising a crank rod havingopposite end regions one of which has pivotal eccentric drivingconnection with said shaft; a driving link having opposite end regionsone of which has pivotal driving connection with said piston on a locuslying along the second axis; and guided pivot means pivotallyinterconnecting the respective remaining end regions of said crank rodand link, together with pivot-guiding means adjustable to selectablefixed positions cooperative with said guided pivot means to constrainthe motion of the latter in said positions along an arcuate pathextending along an arc of circle which intercepts the center of saidfirst axis in all of said fixed positions and is effective responsive torotation of said shaft to cause reciprocation of the piston with full orlost-motion in a stroke the magnitude of which lies between zero andpredetermined maximum limits depending upon the selected fixed angulardisposition of said path relative to said second axis, at least.

2. Mechanism according to claim 1 wherein said pivot guiding means isitself concentrically rotatable into said selectable positions about theshaft axis to orient said arcuate path in changed angular relation tosaid second axis with resultant change in the magnitude of the pistonstroke between the limits aforesaid.

3. Pump mechanism comprising, in combination with a cylinder and apiston reciprocable therein, drive means including a driving eccentricrotatable about an axis extending in a direction laterally of the axisof the cylinder and piston travel and situated adjacent a particular endof the cylinder at which a driving connection with the piston iseffected; crank means driven by said eccentric; link means drivinglyinterconnecting with said piston to provide the driving connectionaforesaid; and pivot means drivingly interconnecting said link meanswith said crank means; guide means mounted to turn concentrically aboutsaid eccentric axis into selectedpositions and affording an arcuateguideway extending in a generally lateral sense relative to saideccentric and piston axes in a region adjacent said particular endregion of the cylinder; and guided means having a coaxial relationshipwith said pivot means and guided relationship with said guideway suchthat rotation of the eccentric imparts reciprocatory drive to said linkmeans and piston in a magnitude ranging between zero and a maximumdepending upon the angular attitude of said guide means relative to saidpiston axis in the selected positions aforesaid.

4. Mechanism according to claim 3 further characterized in that saidguide means is rotatively adjustable about said eccentric to change saidangular attitude of the guide means whereby the magnitude ofdisplacement of the piston can be progressively changed throughout saidrange.

5. In metering pumps and the like having a cylinder, a pistonreciprocable therein, and rotary shaft means for reciprocating saidpiston, stroke-adjusting drive means interconnecting said shaft andpiston and com prising: an eccentric rotated by said shaft; an adjustment member and means mounting the same to turn into selected angularadjustment positions concentrically about the axis of said shaft andeccentric; arcuately extending guide means forming a fixed integrallyconformed part of said adjustment member with the arc thereof containingthe locus of a point which intercepts said shaft axis in all angularpositions of said adjustment member; crank means having one end regionpivotally connecting with said eccentric and a further end region whichis adapted to follow the arc of said guide means in rotation of theeccentric; link means having one end region pivotally connecting with anend region of said piston and having a further end region which is alsoadapted to follow the arc of said guide means in interconnection withsaid crank means; means pivotally interconnecting the respective saidfurther end regions of the crank means and link means; and guided meansmovable with and concentric with said interconnecting means andconstrained by said guide means to oscillate along the arc thereofresponsive to rotation of said eccentric in displacements of variablemagnitude depending upon the angular setting of said adjustment member,whereby the stroke of said piston may be varied between zero and apredetermined maximum displacement; together with means operative tosecure the adjustment member in any selected adjustment position.

6. Apparatus acording to claim 5 wherein said link means is a dog-leglever characterized in that said further end region thereof is offsetangularly from the first mentioned end region thereof for pivotalconnection with the piston as aforesaid; and said shaft axis is situated to extend at right angles to the axis of piston travel and along alocus at one side of said piston axis.

7. Pump apparatus according to claim 5 wherein said adjustment member isa disc-like molded plastic member having a central opening fittingfreely about said eccentric means concentrically of the axis aforesaid,and said guide means is an arcuate channel conformed with said member inposition to extend relative to the axis and eccentric in the manneraforesaid, and said guided means includes a part guidedly constrained totravel in said channel.

8. Apparatus according to claim 7 wherein said plastic member is furtherprovided with an integrally conformed annular collar protuberant fromone side thereof concentrically with said central opening therein andseating rotatively in support means disposing the same concentricallyrelative to said axis and eccentric in the manner aforesaid.

UNITED STATES PATENT OFFICE 7 ERTIFICATE OF CORRECTION Patent No.3,834,839 Dated September 10, 1974 u; InventorQsM Frank Krebs andFrederick N. Zimmermann It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

On the first page of the patent before 22] Filedj Aug. 30, 1971" insert[73] Assignee: March Manufacturing Company, Glenview,

Hlinois"; column 2, line 68, for "materials read --material--.

Signed and sealed this 18th day of February 1975.

(SEAL) Attest:

a C. MARSHALL DANN RUTH C. MASON Commissioner of Patents AttestingOfficer and Trademarks USCOMM-DC 6O376-P69 u.sv GOVERNMENT PRINTINGOFFICE: mu o-Jes-aal,

F ORM PO-1050 (10-69)

1. In a pump for metering chemical solutions of caustic and acidiccharacter, a cylinder, a piston reciprocable in said cylinder, drivemeans including a shaft rotatable about a first axis extending in adirection at one side of and at right angles to a second axis relativeto which the piston reciprocates, and variable-stroke mechanismdrivingly interconnecting said shaft anD piston and comprising a crankrod having opposite end regions one of which has pivotal eccentricdriving connection with said shaft; a driving link having opposite endregions one of which has pivotal driving connection with said piston ona locus lying along the second axis; and guided pivot means pivotallyinterconnecting the respective remaining end regions of said crank rodand link, together with pivot-guiding means adjustable to selectablefixed positions cooperative with said guided pivot means to constrainthe motion of the latter in said positions along an arcuate pathextending along an arc of circle which intercepts the center of saidfirst axis in all of said fixed positions and is effective responsive torotation of said shaft to cause reciprocation of the piston with full orlost-motion in a stroke the magnitude of which lies between zero andpredetermined maximum limits depending upon the selected fixed angulardisposition of said path relative to said second axis, at least. 2.Mechanism according to claim 1 wherein said pivot guiding means isitself concentrically rotatable into said selectable positions about theshaft axis to orient said arcuate path in changed angular relation tosaid second axis with resultant change in the magnitude of the pistonstroke between the limits aforesaid.
 3. Pump mechanism comprising, incombination with a cylinder and a piston reciprocable therein, drivemeans including a driving eccentric rotatable about an axis extending ina direction laterally of the axis of the cylinder and piston travel andsituated adjacent a particular end of the cylinder at which a drivingconnection with the piston is effected; crank means driven by saideccentric; link means drivingly interconnecting with said piston toprovide the driving connection aforesaid; and pivot means drivinglyinterconnecting said link means with said crank means; guide meansmounted to turn concentrically about said eccentric axis into selectedpositions and affording an arcuate guideway extending in a generallylateral sense relative to said eccentric and piston axes in a regionadjacent said particular end region of the cylinder; and guided meanshaving a coaxial relationship with said pivot means and guidedrelationship with said guideway such that rotation of the eccentricimparts reciprocatory drive to said link means and piston in a magnituderanging between zero and a maximum depending upon the angular attitudeof said guide means relative to said piston axis in the selectedpositions aforesaid.
 4. Mechanism according to claim 3 furthercharacterized in that said guide means is rotatively adjustable aboutsaid eccentric to change said angular attitude of the guide meanswhereby the magnitude of displacement of the piston can be progressivelychanged throughout said range.
 5. In metering pumps and the like havinga cylinder, a piston reciprocable therein, and rotary shaft means forreciprocating said piston, stroke-adjusting drive means interconnectingsaid shaft and piston and comprising: an eccentric rotated by saidshaft; an adjustment member and means mounting the same to turn intoselected angular adjustment positions concentrically about the axis ofsaid shaft and eccentric; arcuately extending guide means forming afixed integrally conformed part of said adjustment member with the arcthereof containing the locus of a point which intercepts said shaft axisin all angular positions of said adjustment member; crank means havingone end region pivotally connecting with said eccentric and a furtherend region which is adapted to follow the arc of said guide means inrotation of the eccentric; link means having one end region pivotallyconnecting with an end region of said piston and having a further endregion which is also adapted to follow the arc of said guide means ininterconnection with said crank means; means pivotally interconnectingthe respective said further end regions of the crank means and linkmeans; and guided means movable with and concenTric with saidinterconnecting means and constrained by said guide means to oscillatealong the arc thereof responsive to rotation of said eccentric indisplacements of variable magnitude depending upon the angular settingof said adjustment member, whereby the stroke of said piston may bevaried between zero and a predetermined maximum displacement; togetherwith means operative to secure the adjustment member in any selectedadjustment position.
 6. Apparatus acording to claim 5 wherein said linkmeans is a dog-leg lever characterized in that said further end regionthereof is offset angularly from the first mentioned end region thereoffor pivotal connection with the piston as aforesaid; and said shaft axisis situated to extend at right angles to the axis of piston travel andalong a locus at one side of said piston axis.
 7. Pump apparatusaccording to claim 5 wherein said adjustment member is a disc-likemolded plastic member having a central opening fitting freely about saideccentric means concentrically of the axis aforesaid, and said guidemeans is an arcuate channel conformed with said member in position toextend relative to the axis and eccentric in the manner aforesaid, andsaid guided means includes a part guidedly constrained to travel in saidchannel.
 8. Apparatus according to claim 7 wherein said plastic memberis further provided with an integrally conformed annular collarprotuberant from one side thereof concentrically with said centralopening therein and seating rotatively in support means disposing thesame concentrically relative to said axis and eccentric in the manneraforesaid.